1. Field of the Invention
The present invention relates to a liquid jet head for ejecting liquid from a nozzle to record graphics and characters on a recording medium, or to form a functional thin film thereon. The present invention also relates to a liquid jet apparatus using the liquid jet head.
2. Description of the Related Art
In recent years, there has been used an ink-jet type liquid jet head for ejecting ink droplets on recording paper or the like to record characters or graphics thereon, or for ejecting a liquid material on a surface of an element substrate to form a functional thin film thereon. In such a liquid jet head, ink or a liquid material is supplied from a liquid tank via a supply tube to the liquid jet head, and ink or a liquid material filled into a channel is ejected from a nozzle which communicates to the channel. When ink is ejected, the liquid jet head or a recording medium on which a pattern of jetted liquid is to be recorded is moved to record characters or graphics, or to form a functional thin film in a predetermined shape.
FIGS. 9, 10A, and 10B are schematic sectional views of an ink jet head 100 of this type described in Japanese Patent Application Laid-open No. 2011-104791. The ink jet head 100 has a laminate structure including a cover 102 provided with ejection holes 103a and 103b, a PZT plate 104 formed of a piezoelectric body, a cover plate 108, and a flow path member 111. The PZT plate 104 has one surface provided with elongated deep grooves 105a, and shallow grooves 105b arrayed adjacent thereto and orthogonal to the elongated direction. The cross section of the deep groove 105a in each of the longitudinal direction and the depth direction has a protruded shape in the depth direction. On an upper part of a side wall of each of the grooves 105a and 105b, an electrode 116 is formed. The cover plate 108 includes a liquid supply duct 109 corresponding to a longitudinal center opening portion of the deep groove 105a, and two liquid discharge ducts 110a and 110b corresponding to opening portions at both longitudinal ends of the deep groove 105a. 
The ink jet head 100 operates as follows. Liquid supplied from the liquid supply duct 109 flows into the deep grooves 105a and 105c. Further, the liquid flowing out from the deep grooves 105a and 105c is discharged from the liquid discharge ducts 110a and 110b, and thus the liquid is circulated without stagnation. The drive electrode 116 formed on the wall surface of the side wall for sectioning the deep groove 105c and the shallow groove 105b is electrically separated at a longitudinal center portion of each of the deep groove 105c and the shallow groove 105b. When the liquid is jetted from the ejection hole 103a, a drive voltage is applied to the drive electrode on the ejection hole 103a side to deform the side wall on the ejection hole 103a side. When the liquid is jetted from the ejection hole 103b, a drive voltage is applied to the drive electrode on the ejection hole 103b side to deform the side wall on the ejection hole 103b side. Further, the shallow grooves 105b are formed across the deep groove 105a, and are closed by the cover plate 108 so as to prevent the liquid from entering the shallow grooves 105b. Therefore, conductive liquid can be used, and the side wall of each deep groove 105a can be controlled independently from the drive of the adjacent deep groove. That is, liquid can be independently jetted from two nozzles, and the deep groove is not affected by the drive voltage for driving the adjacent deep groove. Therefore, the recording density and the recording speed can be improved.
However, in the above-mentioned conventional example of FIGS. 9, 10A, and 10B, in order to increase the resolution, the deep groove 105a is provided with two ejection holes 103a and 103b. Therefore, when liquid is ejected from one ejection hole 103a, the liquid may also be ejected from the other ejection hole 103b. 
Further, due to a pressure wave generated when a voltage is applied to the side wall to drive the drive electrode for ejection from one ejection hole, the liquid may be ejected from the other ejection hole. In addition, the pressure wave may affect a pressure wave generated when the drive electrode is driven for ejection from the other ejection hole to cause wave overlapping. Thus, stable ejection cannot be performed, and hence an advanced drive voltage control has been required.